There is very little available to a homeowner or gardener to help him do a most difficult physical task--sift the soil before planting. There are many rototiller devices available and there are many people available to do rototilling as a service for individuals; however, once the soil is tilled the backbreaking work begins. There is very little available to accomplish shifting the soil to clean it of debris before replanting. What one normally has to do is rake the tilled soil pulling out the large rocks and stones one by one and shaking the clumps of grass to remove the topsoil and then releveling the ground and raking it until it is smooth and uniform, seeding, rolling it to plant grass or rows of vegetables follows. This invention does the work between tilling and planting. Another common practice after an area is tilled is to scrape off the topsoil and manually sift it and return it to where it was removed, relevel and then seed. Both practices are backbreaking work. The latter is, of course, the most useful.
The present invention solves the problem of removing, sifting and releveling the soil once tilled by having a self-propelled power-driven vibrating sifting device which penetrates the soil to controlled depths as it passes over the garden, removes the stone and other debris from the soil and redeposits the sifted soil below the device and carries the debris to one end of the yard for later removal. More than one pass may be needed in heavily weeded rocky soil, but the soil is never moved any distance saving a lot of effort.
The soil is sifted in place such that minimal leveling is required after the soil has been sifted, evenly with more than one pass. Piles of debris, rock, weeds and other clumps of soil are screened out and left to be picked up by a truck at one end of the garden.
Having established the need for a power sifter, several obstacles were presented. The first was guiding the device in a straight direction while sifting the soil. It was discovered that a vibrator that sifted left to right in equal and opposite directions balanced the turning or twisting torque on the sifter and did not pull the device either to the left or right and went straight ahead in perfect control.
It was also quickly discovered that the screens filled up too soon in many cases. A plow type configuration was best found because when it filled up the sifting could be stopped and the sifter lifted out of the soil and pushed to the end of the row, emptied and pulled back where sifting commenced once again. A device that was pulled in back of a tractor filled too quickly, not easily emptied where wanted and not easily controlled.
A sifter must be propelled by a gasoline motor. However, it was discovered that a hydrostatic motor was essential to control the operation smoothly, consistently and uniformly. The vibration can be provided by a power "take off" from the gas engine while a hydrostatic motor powers the wheels to propel the sifter along.
At first, tines were thought necessary to dig and rake into the ground. However, it was discovered selected steel mesh of about a one-half inch grid welded to a frame with a sharp bending edge was perfectly satisfactory. Finer sifting is controlled by selecting a finer mesh. An optimum mesh was found to be one-half inch or slightly larger.
There are many prior art devices that have been developed to power rake or dethatch an area. These devices remove some rocks and/or the thatch so that grass will grow better. Neither of these devices actually sift the soil. There comes a time when one must remove all the big stones and growing roots, brush and grass, as well as weeds. This is when a power sifter is needed.
Therefore, an object of the present invention is to sift soil in place to remove unwanted rocks and other debris without moving the soil from its place in the garden.
Another object of the present invention is to be able to make several passes at the soil to controlled depths to remove debris, stone and unwanted vegetation with several passes in order to produce a topsoil clean to the satisfaction of the operator and/or needs of the gardener.
Another object of the present invention is to be able to control sifting independent of the movement of the device over a garden.
Another object of the present invention is to separate the stones from the vegetation.
Another object of the present invention is to boil the vegetation material into compact bundles.